<html>
    <head>
        <title>Test</title>
        <style>

body { 
  background: url(https://html-notepad.com/wp-content/uploads/2018/10/cropped-calm-1.jpg) no-repeat;
  background-size: auto 120%;
  overflow: scroll-indicator;
}

        </style>
        <script type="text/tiscript">

$(body).onScroll = function(evt) {
  if( evt.type == Event.SCROLL_POS ) {
    var ratio = evt.scrollPos.toFloat() / this.box(#height,#content);
    this.style#background-position-top = pr(ratio * 100);
  }
}

        </script>
    </head>
    <body>

       <p>content</p>
       <p>content</p>
       <p>content</p>
       <p>content</p>
       <p>content</p>
       <p>content</p>
       <p>content</p>
       <p>content</p>
       <p>content</p>
       <p>content</p>
       <p>content</p>
       <p>content</p>
       <p>content</p>
       <p>content</p>
       <p>content</p>
       <p>content</p>
       <p>content</p>
       <p>content</p>
       <p>content</p>
       <p>content</p>
       <p>content</p>
       <p>content</p>
       <p>content</p>
       <p>content</p>

    </body>
</html>